High-volume centers have better outcomes than low-volume centers when managing complex conditions including subarachnoid hemorrhage (SAH).
To quantify SAH volume-outcome association and determine the extent to which this association is influenced by aggressiveness of care.
A serial cross-sectional retrospective study using the Nationwide Inpatient Sample for 2002 to 2010 was performed. Included were all adult (older than 18 years of age) discharged patients with a primary diagnosis of SAH admitted from the emergency department or transferred to a discharging hospital; cases of trauma or arteriovenous malformation were excluded. Survey-weighted descriptive statistics estimated temporal trends. Multilevel logistic regression estimated volume-outcome associations for inpatient mortality and discharge home. Models were adjusted for demographic characteristics, year, transfer status, insurance status, all individual Charlson comorbidities, intubation, and all patient-refined, diagnosis-related group mortality. Analyses were repeated, excluding cases in which aggressive care was not pursued.
A total of 32 336 discharges were included; 13 398 patients underwent clipping (59.1%) or coiling (40.9%). The inpatient mortality rate decreased from 32.2% in 2002 to 22.2% in 2010; discharge home increased from 28.5% to 40.8% during the same period. As SAH volume decreased from 100/year, the mortality rate increased from 18.7% to 19.8% at 80/year, 21.7% at 60/year, 24.5% at 40/year, and 28.4% at 20/year. As SAH patient volume decreased, the probability of discharge home decreased from 40.3% at 100/year to 38.7% at 60/year, and 35.3% at 20/year. Better outcomes persisted in patients receiving aggressive care and in those not receiving aggressive care.
Short-term SAH outcomes have improved. High-volume hospitals have more favorable outcomes than low-volume hospitals. This effect is substantial, even for hospitals conventionally classified as high volume.
APR-DRG, all patient-refined, diagnosis-related groups
CI, confidence interval
CSC, Comprehensive Stroke Center
ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification
NIS, Nationwide Inpatient Sample
SAH, subarachnoid hemorrhage